Problem of Mold behind pitched roof Sheathing

[Pegahbe]

Hello,
I am modelling a ventilated pitched roof with cellulose insulation between rafters and using a 13mm thick timber sheathing board with sd=0.143m (mu=11) toward outside working also as a vapour permeable layer (sheathing board is located next to the 46mm ventilated air layer), other external parameters are set as attached file.
The analysis results show the water content of more than 20 mass percent for both sheathing board and Cellulose layer close to the sheathing in cold months, and Wufi Bio shows red traffic light constantly for them with mould index more than 3 (the traffic light is red for all 5 years of analysing the model).
I had a search in internet about mold in cellulose, apparently since borate is used for treating cellulose, there is no risk of developing mold for cellulose, but there is the risk of mold for the timber sheathing adjacent to it.
I was wondering if this is a serious problem and I should be worried about it or since the sheathing is next to the ventilated air cavity, all the produced moisture would dry out fast, in other words, WUFI is being cautious and is showing the amount of mold more than what may happen in reality?
Many thanks for your help,
Pegah.